Unstable intermediates. Part XCIV. Hyperfine coupling and zero-field splitting for nitrogen atoms in γ-irradiated azides

Abstract

Exposure of sodium azide to ⁶⁰Co γ-rays at 77 K gave an e.s.r. spectrum dominated by hyperfine components previously assigned to F-centres. On careful annealing these centres are destroyed, revealing features characteristic of trapped nitrogen atoms. At 77 K, A(¹⁴N)= 5·7 G, D= 64 G and E=(–) 8 G, but on warming to about 160 K the spectrum change reversibly to give D= 37 G and E= 0. All parameters decreased slightly on warming the samples.

Similar results were obtained for potassium azide except that no F-centres were detected. The results are discussed in terms of slight admixtures of the nitrogen 2s orbital into the ⁴S ground-state of the atoms.